JPH10281325A - Solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of stress caused by a thermal expansion difference between a bobbin and a core, and make suppressing possible of heat generation caused by an eddy current, while ensuring good heat radiating property of the bobbin. SOLUTION: A bobbin 60 constituting an electromagnetic coil is fixed to the inside of a core. The bobbin 60 is constituted of metal material, so as to have excellent heat radiating property. In the bobbin 60, a slit 68 over an axial direction total length is formed. Consequently, a thermal expansion difference between the bobbin 60 and the core, by elastically deforming the bobbin 60 so as to open/close the slit 68, is absorbed. By providing the slit 68, an eddy current generated in the bobbin 60 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve, and more particularly, to a solenoid valve in which a bobbin of an electromagnet is made of a metal material.

[0002]

2. Description of the Related Art A solenoid valve opens and closes a valve by driving a valve body with an electromagnet. Generally, an electromagnet is configured by winding a coil around a bobbin. The bobbin is often made of a resin material in terms of insulation and moldability. However, since the resin material has a low thermal conductivity, a large temperature rise occurs due to heat generated by energization of the coil. For this reason, for example, in the electromagnet disclosed in JP-A-8-148331,
The heat dissipation of the bobbin is improved by forming the bobbin from a metal material.

[0003]

Generally, in a solenoid valve, a bobbin is fixed inside a core in order to efficiently transmit a magnetic flux generated by a coil to a valve body. Therefore, when heat is generated in the bobbin, stress is generated in the bobbin due to a difference in thermal expansion coefficient between the bobbin and the core. In this case, if the bobbin is made of a metal material as in the above-described conventional electromagnet, the rigidity of the bobbin increases, so that the stress generated in the bobbin increases. Such an increase in stress leads to inconvenience such as a decrease in durability of the bobbin.

[0004] When the bobbin is made of a metal material, an eddy current is generated in the bobbin when the energization state of the coil changes. The generation of such an eddy current causes a decrease in the responsiveness of the solenoid valve. The present invention has been made in view of the above points, while ensuring good heat radiation of the bobbin,
An object of the present invention is to provide an electromagnetic valve capable of suppressing generation of stress due to a difference in thermal expansion between a bobbin and a core and suppressing eddy current.

[0005]

The above object is achieved by the present invention.
As described in the above, in an electromagnetic valve including an electromagnet having a core, a bobbin housed in the core, and a valve body driven by the electromagnet, the bobbin is made of a metal material, and the bobbin is This is achieved by a solenoid valve provided with a slit over the entire length in the direction.

In the present invention, the bobbin is made of a metal material. Generally, the thermal conductivity of a metal material is large. Therefore, heat generated by the coil is quickly radiated from the bobbin. The bobbin is provided with a slit extending over the entire length in the axial direction. Therefore, when a thermal expansion difference occurs between the bobbin and the core, the stress generated in the bobbin is reduced by elastically deforming the bobbin so that the slit opens and closes.
Further, since the slit is formed over the entire length of the bobbin, the resistance value to the eddy current generated in the circumferential direction of the bobbin increases. Thereby, the eddy current generated in the bobbin is suppressed to a small value.

[0007]

FIG. 1 shows a configuration of a solenoid valve 10 according to one embodiment of the present invention. In FIG. 1, a solenoid valve 10 of this embodiment is applied as an intake valve (right side in the figure) and an exhaust valve (left side in the figure) of an internal combustion engine. As shown in FIG. 1, the solenoid valve 10 includes a valve body 12. The valve body 12 constitutes an intake valve or an exhaust valve of the internal combustion engine. The valve body 12 is mounted on a cylinder head 14 so that the valve body 12 is
It is arranged in. An intake port 16 and an exhaust port 18 are formed in the cylinder head 14. The intake port 16 and the exhaust port 18 have a valve seat 2 for the valve body 12.
0 is formed. Intake port 16 and exhaust port 1
Each of the valves 8 is in a conductive state when the valve body 12 is separated from the valve seat 20, and is in a closed state when the valve body 12 is seated on the valve seat 20.

A valve shaft 24 is fixed to the valve body 12.
The valve shaft 24 is held by a valve guide 26 so as to be slidable in the axial direction. The valve guide 26 is the cylinder head 1
4 is held. A cylindrical portion 28 is formed in a portion of the cylinder head 14 surrounding a substantially upper half of the valve shaft 24.
A lower retainer 30 is fixed to an upper end of the valve shaft 24. Between the lower retainer 30 and the bottom surface of the cylindrical portion 28, a lower spring 32 that generates an urging force in a direction for separating the lower retainer 30 and the cylindrical portion 28 is provided. The lower spring 32 urges the valve shaft 24 and the valve body 12 upward through the lower retainer 30, that is, urges the valve body 12 toward the valve seat 20. Hereinafter, the direction in which the valve body 12 faces the valve seat 20 will be referred to as the valve body 1.
2 or the valve closing direction of the valve shaft 24, and the direction in which the valve body 12 moves away from the valve seat 20 is referred to as the valve opening direction of the valve body 12 or the valve shaft 24.

A cylindrical portion 29 having a diameter larger than that of the cylindrical portion 28 and coaxial with the cylindrical portion 28 is formed inside the cylinder head 14 above the cylindrical portion 28. A plunger 36 is disposed coaxially with the valve shaft 24 in the cylindrical portion 29. As the valve shaft 24 is urged by the lower spring 32, the upper end surface of the valve shaft 24 is pressed against the lower end surface of the plunger 36. An upper retainer 38 is fixed to the upper end of the plunger 36. Apparitainer 38
The lower end of the upper spring 40 is in contact with the upper part of the upper part. A cylindrical upper cap 42 is provided around the upper spring 40. Upper cap 42
Is fixed to the upper surface of the cylinder 14 by a fixing bolt (not shown). An adjuster bolt 44 is screwed onto the upper portion of the upper cap 42. Upper spring 4
The upper end of 0 is in contact with the adjuster bolt 44. The upper spring 40 urges the plunger 36 downward via the retainer 38. In addition, a head cover 45 is provided on the upper part of the cylinder head 14 with each solenoid valve 1.
It is fixed so as to cover two upper caps 42 corresponding to “0”.

An armature 46 is fixed to an outer periphery of a central portion of the plunger 36 in the axial direction. The surface of the armature 46 is hard-plated such as electroless Ni-P plating or hard chrome plating having a thickness of about 20 to 50 μm, or
The nitriding treatment is performed to a depth of about 20 to 50 μm.
Above the armature 46, a first core 48 is provided. Further, a second core 52 is provided below the armature 46. The first core 48 and the second core 52 are press-fitted and fixed to the cylindrical portion 29 of the cylinder head 14. First
Annular grooves 48a and 52a are formed on the surfaces of the core 48 and the second core 52 facing the armature 46, respectively. First electromagnetic coils 54 and 55 are disposed inside the annular grooves 48a and 52a, respectively. First
The electromagnetic coils 54 and 55 are configured by winding coils around the first bobbin 56 and the second bobbin 58, respectively. The inner peripheral surfaces of the first bobbin 56 and the second bobbin 58 respectively correspond to the first core 48 and the second core 5.
The second annular grooves 48 a and 52 a are fixed inside the first core 48 and the second core 52 by being press-fitted into the inner walls on the inner diameter side.

Hereinafter, when the first bobbin 56 and the bobbin 58 are not distinguished, they are generically referred to as a bobbin 60. When the first electromagnetic coil 54 and the second electromagnetic coil 55 are not distinguished, they are collectively referred to as an electromagnetic coil 61,
When the first core 48 and the second core 52 are not distinguished,
It is generically referred to as a core 62. Next, the configuration of the bobbin 60 will be described with reference to FIGS. FIG. 2 is a diagram of the bobbin 60 viewed from its axial direction. FIG. 3 is a sectional view of the bobbin 60 taken along a line III-III shown in FIG.

As shown in FIGS. 2 and 3, the bobbin 60 is
It comprises a cylindrical main body 64 and annular flanges 65 and 66 provided at both axial ends of the main body 64. The bobbin 60 is made of a metal material having a high thermal conductivity, such as a copper-based material or a stainless steel material.
The bobbin 60 is provided with a slit 68. The slit 68 includes the flange 65, the main body 64, and the flange 6.
6 is formed so as to extend longitudinally over the entire length of the bobbin 60 in the axial direction. A cutout 69 is formed in one flange 65. The winding of the electromagnetic coil 61 is wound around the outer periphery of the main body 64, and both ends are taken out of the notch 69 to the outside. Further, the outer peripheral portion of the winding is molded with a resin having a good thermal conductivity.

An insulating film is provided on the surface of the bobbin 60. Thereby, when the coating of the winding of the electromagnetic coil 61 is peeled off, short-circuit between the winding and the winding via the bobbin 60 is prevented. The insulating film is formed to be as thin as possible, for example, several tens of μm thick, in order to prevent a decrease in the thermal conductivity of the bobbin 60. As the insulating film, for example, a film formed by an insulating varnish treatment, an organic film formed by applying a water-soluble acrylic resin or a resin to which an inorganic component is added, or a zinc phosphate film is applied. An inorganic film formed by such a method is suitable.

Referring again to FIG. 1, the first core 48 and the second core 52 are provided with through holes 48b and 52b, respectively, passing through the central portions thereof. A first bearing 56 is provided at an upper end of the through hole 48b of the first core 48. In addition, a second end is provided at the lower end of the through hole 52b of the second core 52.
A bearing 58 is provided. First bearing 56
The second bearing 58 is a sliding bearing made of a cylindrical metal member or a resin member. Plunger 3
6 is held by a first bearing 56 and a second bearing 58 so as to be slidable in the axial direction. The above-described adjuster bolt 44 is adjusted so that the neutral position of the armature 46 is located at an intermediate point between the first core 48 and the second core 54.

Next, the operation of the solenoid valve 10 will be described. When the exciting current is supplied to the first electromagnetic coil 54, the armature 4 is generated by the magnetic flux generated by the first electromagnetic coil 54.
Electromagnetic force in the direction toward the first core 48 acts on 6.
Therefore, as shown in FIG. 1, the armature 46 resists the urging force of the upper spring 40 so that the first core 4
The valve body 12 is seated on the valve seat 20 until it comes into contact with the valve seat 8. When the exciting current is supplied to the first electromagnetic coil 54, the electromagnetic valve 10 is closed. The position at which the armature 46 contacts the first core 48 is hereinafter referred to as the armature 46, the plunger 36, the valve shaft 24, or the valve-closing-side displacement end of the valve body 12.

When the supply of the exciting current to the first electromagnetic coil 54 is stopped in the state where the solenoid valve 10 is closed as described above, the electromagnetic force required to hold the armature 46 at the valve-closing-side displacement end. Power disappears. In this case, as described above, since the hard plating process or the nitriding process is performed on the surface of the armature 46, an attractive force acts between the armature 46 and the first core 48 due to residual magnetism inside the armature 46. That has been prevented. Therefore, when the supply of the exciting current to the first electromagnetic coil 54 is stopped, the plunger 36 is immediately urged by the upper spring 40 to start displacing downward together with the valve shaft 24. When the valve shaft 24 is displaced downward from the valve-closing-side displacement end, the valve body 12 is separated from the valve seat 20 and the solenoid valve 10 is opened. When the exciting current is supplied to the second electromagnetic coil 55 when the amount of displacement of the plunger 36 reaches a predetermined value, an electromagnetic force for urging the armature 46 toward the second core 52 is generated.

When the electromagnetic force acts on the armature 46, the armature 46 is displaced until it comes into contact with the second core 52 against the urging force generated by the lower spring 32, and the valve body 12 is displaced in the valve opening direction. The amount is maximum. Hereinafter, the position where the armature 46 abuts on the second core 52 is referred to as the armature 46, the plunger 36, the valve shaft 24, or the valve-opening-side displacement end of the valve body 12. In this state, the second electromagnetic coil 55
When the supply of the exciting current to is stopped, the electromagnetic force necessary to hold the armature 46 at the valve-opening-side displacement end is extinguished.
Also in this case, since the hard plating process or the nitriding process is performed on the surface of the armature 46, the valve body 12 and the plunger 36 immediately start displacing upward by the urging force generated by the lower spring 28. When an exciting current is supplied to the first electromagnetic coil 54 at the time when these displacement amounts reach a predetermined value, the armature 46 is urged toward the first core 48 by the electromagnetic force generated by the first electromagnetic coil 54. .
For this reason, the valve shaft 12 and the plunger 36 are displaced to the valve-closing-side displacement end, and the solenoid valve 10 is closed again when the valve body 12 is seated on the valve seat 20.

As described above, according to the present embodiment, the exciting current is alternately supplied to the first electromagnetic coil 54 and the second electromagnetic coil 55 at an appropriate timing, so that the valve body 12 is brought into the closed position. The electromagnetic valve 10 can be opened and closed by repeatedly reciprocating with the valve-opening-side displacement end. As described above, the solenoid valve 10 of the present embodiment is driven by supplying the exciting current to the solenoid coil 61. For this reason,
With the operation of the solenoid valve 10, heat is generated in the solenoid coil 61 due to the exciting current. In particular, when an attempt is made to generate a large driving force on the valve body 12 while reducing the size of the electromagnetic valve 10, the exciting current applied to the electromagnetic coil 61 increases, and the heat generation increases. In such a case,
If the heat radiation from the electromagnetic coil 61 is not sufficiently performed, an excessive temperature rise occurs in the electromagnetic coil 61.

On the other hand, in the present embodiment, as described above, the bobbin 60 is made of a metal material having high thermal conductivity such as a copper-based material or a stainless-based material. Therefore, the heat generated in the electromagnetic coil 61 is quickly transmitted to the core 62 via the bobbin 60, and further transmitted from the core 62 to the cylinder head 14. As described above, according to the present embodiment, the heat generated in the electromagnetic coil 61 is quickly radiated to the cylinder head 14, so that the temperature rise of the electromagnetic coil 61 is suppressed. Note that, as described above, the bobbin 60
The thickness of the insulating film formed on the surface of the bobbin is suppressed to a small value, and the heat radiation of the bobbin 60 is further improved by molding the outer periphery of the winding with a resin having good thermal conductivity. .

However, even though the bobbin 60 has excellent heat radiation, it is not possible to avoid that the temperature of the bobbin 60 rises to some extent due to energization of the electromagnetic coil 61. When the temperature rise on the bobbin 60 occurs,
Due to the difference in the coefficient of thermal expansion between the bobbin 60 and the core 62,
Both have different thermal expansions. As described above, bobbin 6
0 is press-fitted and fixed to the core 62, so that if a different thermal expansion occurs between the bobbin 60 and the core 62, the bobbin 60
Generates stress. In particular, in this embodiment, since the bobbin 60 is made of a metal material, the rigidity of the bobbin 60 increases when the bobbin 60 has a closed structure such as a completely cylindrical shape. A large stress easily occurs due to the difference. The generation of such stress is caused by
Inconveniences such as a decrease in durability of 0 are caused.

On the other hand, in this embodiment, the slit 68 is formed in the bobbin 60 over the entire length in the axial direction. Therefore, the difference in thermal expansion between the bobbin 60 and the core 62 is absorbed by the bobbin 60 being elastically deformed so that the slit 68 opens and closes. That is, in the present embodiment, the provision of the slit 68 reduces the rigidity of the bobbin 60 in the circumferential direction, thereby alleviating the stress generated in the bobbin 60. As described above, according to the solenoid valve 10 of the present embodiment, by providing the slit 68, the rigidity of the bobbin 60 can be reduced while the bobbin 60 is formed of a metal material. It is possible to alleviate the occurrence of stress due to the difference in thermal expansion between the two.

In the solenoid valve 10 of the present embodiment,
Since the bobbin 60 is made of a metal material, an eddy current is generated in the bobbin 60 when the energization state of the electromagnetic coil 61 changes. The eddy current flows in such a direction as to cancel the change in the magnetic flux generated by the electromagnetic coil 61. That is,
The eddy current flows mainly in the circumferential direction of the bobbin 60. In the present embodiment, the bobbin 60 is made of a non-magnetic material such as a copper-based material or a non-magnetic stainless material to suppress the eddy current. However, the eddy current cannot be completely eliminated. For this reason, an eddy current is generated in the bobbin 60 according to the opening / closing operation of the solenoid valve 10, and particularly when the solenoid valve 10 is operated at a high speed, a decrease in responsiveness due to the eddy current cannot be ignored.

On the other hand, in the present embodiment, since the slit 68 is formed in the bobbin 60 over the entire length in the axial direction, the flow path of the eddy current circulating in the bobbin 60 in the circumferential direction is blocked. For this reason, when the eddy current generated in the bobbin 60 reaches the slit 68, its direction is reversed, and flows on both sides of the slit 68 so as to reciprocate over substantially the entire circumference of the bobbin 60. As a result, the length of the flow path of the eddy current increases, and the effective resistance value to the eddy current increases. Therefore, according to the solenoid valve 10 of the present embodiment, the generation of the eddy current itself is suppressed by the bobbin 60 being made of a non-magnetic material, and in addition, the formation of the slit 68 reduces the eddy current. The increase in the resistance value also suppresses the eddy current to a small value. As described above, in the present embodiment, the eddy current is suppressed from both the material side and the form side of the bobbin 60, so that the eddy current suppressing effect is improved.

In this embodiment, a non-magnetic material is used as a constituent material of the bobbin 60 in order to suppress the eddy current from the material side. However, even a magnetic material having a large specific resistance value is used. If so, the eddy current can be similarly suppressed. As described above, according to the solenoid valve 10 of the present embodiment, the bobbin 60 is made of a metal material, so that excellent heat radiation of the bobbin 60 can be realized. Further, by forming the slit 68 in the bobbin 60, it is possible to suppress the stress generated in the bobbin 60 due to the difference in thermal expansion between the bobbin 60 and the core 62, and to suppress the eddy current generated in the bobbin 60. it can.

In the above embodiment, the case where the solenoid valve according to the present invention is applied as an intake valve and an exhaust valve of an internal combustion engine has been described. However, the present invention is not limited to this, The present invention can be applied to any other electromagnetic valve such as an electromagnetic on-off valve for a circuit.

[0026]

As described above, according to the present invention, the bobbin is made of a metal material, thereby ensuring excellent heat radiation of the bobbin, and at the same time, the bobbin is formed on the bobbin due to the difference in thermal expansion between the bobbin and the core. The stress can be alleviated, and the eddy current generated in the bobbin can be suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram when an electromagnetic valve according to an embodiment of the present invention is applied as an intake valve and an exhaust valve of an internal combustion engine.

FIG. 2 is a view of a bobbin included in the solenoid valve of the present embodiment as viewed from an axial direction.

FIG. 3 is a cross-sectional view of the bobbin shown in FIG. 2 taken along a line III-III.

[Explanation of symbols]

 Reference Signs List 10 electromagnetically driven valve 48 first core 52 second core 54 first electromagnetic coil 55 second electromagnetic coil 56 first bobbin 58 second bobbin 60 bobbin 61 electromagnetic coil 62 core 68 slit

Claims (1)

[Claims] 1. An electromagnetic valve comprising: an electromagnet having a core, a bobbin accommodated in the core, and a valve body driven by the electromagnet, wherein the bobbin is made of a metal material, and a shaft is attached to the bobbin. Solenoid valve characterized by providing a slit over the entire length in the direction.